scholarly journals Peroxisomes Implicated in the Biosynthesis of Siderophores and Biotin, Cell Wall Integrity, Autophagy, and Response to Hydrogen Peroxide in the Citrus Pathogenic Fungus Alternaria alternata

2021 ◽  
Vol 12 ◽  
Author(s):  
Pei-Ching Wu ◽  
Yu-Kun Chen ◽  
Jonar I. Yago ◽  
Kuang-Ren Chung
Keyword(s):  
Cell Wall ◽  
Alternaria Alternata ◽  
Plant Pathogens ◽  
Protein Import ◽  
Fluorescent Protein ◽  
Pathogenic Fungus ◽  
Cell Wall Integrity ◽  
Eosin Y ◽  
Peroxisomal Biogenesis ◽  
Fungal Plant Pathogens

Little is known about the roles of peroxisomes in the necrotrophic fungal plant pathogens. In the present study, a Pex6 gene encoding an ATPase-associated protein was characterized by analysis of functional mutations in the tangerine pathotype of Alternaria alternata, which produces a host-selective toxin. Peroxisomes were observed in fungal cells by expressing a mCherry fluorescent protein tagging with conserved tripeptides serine-lysing-leucine and transmission electron microscopy. The results indicated that Pex6 plays no roles in peroxisomal biogenesis but impacts protein import into peroxisomes. The number of peroxisomes was affected by nutritional conditions and H2O2, and their degradation was mediated by an autophagy-related machinery termed pexophagy. Pex6 was shown to be required for the formation of Woronin bodies, the biosynthesis of biotin, siderophores, and toxin, the uptake and accumulation of H2O2, growth, and virulence, as well as the Slt2 MAP kinase-mediated maintenance of cell wall integrity. Adding biotin, oleate, and iron in combination fully restored the growth of the pex6-deficient mutant (Δpex6), but failed to restore Δpex6 virulence to citrus. Adding purified toxin could only partially restore Δpex6 virulence even in the presence of biotin, oleate, and iron. Sensitivity assays revealed that Pex6 plays no roles in resistance to H2O2 and superoxide, but plays a negative role in resistance to 2-chloro-5-hydroxypyridine (a hydroxyl radical-generating compound), eosin Y and rose Bengal (singlet oxygen-generating compounds), and 2,3,5-triiodobenzoic acid (an auxin transport inhibitor). The diverse functions of Pex6 underscore the importance of peroxisomes in physiology, pathogenesis, and development in A. alternata.

scholarly journals Nonhost Resistance in Arabidopsis-Colletotrichum Interactions Acts at the Cell Periphery and Requires Actin Filament Function

2006 ◽  
Vol 19 (3) ◽  
pp. 270-279 ◽  
Author(s):  
Chiyumi Shimada ◽  
Volker Lipka ◽  
Richard O'Connell ◽  
Tetsuro Okuno ◽  
Paul Schulze-Lefert ◽  
...  
Keyword(s):  
Actin Filament ◽  
Fungal Pathogens ◽  
Plant Pathogens ◽  
Fluorescent Protein ◽  
Molecular Genetic ◽  
Molecular Genetic Analysis ◽  
Nonhost Resistance ◽  
Cell Periphery ◽  
Colletotrichum Species ◽  
Fungal Plant Pathogens

Pathogenesis of nonadapted fungal pathogens is often terminated coincident with their attempted penetration into epidermal cells of nonhost plants. The genus Colletotrichum represents an economically important group of fungal plant pathogens that are amenable to molecular genetic analysis. Here, we investigated interactions between Arabidopsis and Colletotrichum to gain insights in plant and pathogen processes activating nonhost resistance responses. Three tested nonadapted Colletotrichum species differentiated melanized appressoria on Arabidopsis leaves but failed to form intracellular hyphae. Plant cells responded to Colletotrichum invasion attempts by the formation of PMR4/GSL5-dependent papillary callose. Appressorium differentiation and melanization were insufficient to trigger this localized plant cell response, but analysis of nonpathogenic C. lagenarium mutants implicates penetration-peg formation as the inductive cue. We show that Arabidopsis PEN1 syntaxin controls timely accumulation of papillary callose but is functionally dispensable for effective preinvasion (penetration) resistance in nonhost interactions. Consistent with this observation, green fluorescent protein-tagged PEN1 did not accumulate at sites of attempted penetration by either adapted or nonadapted Colletotrichum species, in contrast to the pronounced focal accumulations of PEN1 associated with entry of powdery mildews. We observed extensive reorganization of actin microfilaments leading to polar orientation of large actin bundles towards appressorial contact sites in interactions with the nonadapted Colletotrichum species. Pharmacological inhibition of actin filament function indicates a functional contribution of the actin cytoskeleton for both preinvasion resistance and papillary callose formation. Interestingly, the incidence of papilla formation at entry sites was greatly reduced in interactions with C. higginsianum isolates, indicating that this adapted pathogen may suppress preinvasion resistance at the cell periphery.

The insect-derived antimicrobial peptide metchnikowin targets Fusarium graminearum β(1,3)glucanosyltransferase Gel1, which is required for the maintenance of cell wall integrity

2017 ◽  
Vol 398 (4) ◽  
pp. 491-498 ◽  
Author(s):  
Mohammad-Reza Bolouri Moghaddam ◽  
Andreas Vilcinskas ◽  
Mohammad Rahnamaeian
Keyword(s):  
Cell Wall ◽  
Fusarium Graminearum ◽  
Mammalian Cells ◽  
Plant Pathogens ◽  
Fruit Fly ◽  
Phytopathogenic Fungi ◽  
Food Preservation ◽  
Cell Wall Integrity ◽  
Fungal Cell ◽  
Essential Components

Abstract Antimicrobial peptides (AMPs) are essential components of the insect innate immune system. Their diversity provides protection against a broad spectrum of microbes and they have several distinct modes of action. Insect-derived AMPs are currently being developed for both medical and agricultural applications, and their expression in transgenic crops confers resistance against numerous plant pathogens. The antifungal peptide metchnikowin (Mtk), which was originally discovered in the fruit fly Drosophila melanogaster, is of particular interest because it has potent activity against economically important phytopathogenic fungi of the phylum Ascomycota, such as Fusarium graminearum, but it does not harm beneficial fungi such as the mycorrhizal basidiomycete Piriformospora indica. To investigate the specificity of Mtk, we used the peptide to screen a F. graminearum yeast two-hybrid library. This revealed that Mtk interacts with the fungal enzyme β(1,3)-glucanosyltransferase Gel1 (FgBGT), which is one of the enzymes responsible for fungal cell wall synthesis. The interaction was independently confirmed in a second interaction screen using mammalian cells. FgBGT is required for the viability of filamentous fungi by maintaining cell wall integrity. Our study therefore paves the way for further applications of Mtk in formulation of bio fungicides or as a supplement in food preservation.

Topographical signaling for cell differentiation in the plant pathogenic fungus, Uromyces

1989 ◽  
Vol 47 ◽  
pp. 784-785
Author(s):  
H.C. Hoch
Keyword(s):  
Plant Pathogens ◽  
Developmental Process ◽  
Pathogenic Fungus ◽  
Host Cells ◽  
Subsequent Infection ◽  
Infection Structures ◽  
Rust Diseases ◽  
Fungal Plant Pathogens ◽  
Plant Signals ◽  
Important Structure

Fungal plant pathogens invade host cells with a variety of specialized infection structures, however, for most fungi the appressorium is developmentally the first and most important structure to be formed in preparation for host colonization. It must be positioned at an appropriate site on the host in a timely way so that subsequent infection can be assured. For fungi which cause rust diseases of plants, positioning the appressorium is the most critical stage because invasion of the host can occur only via the stomata. Uredospores of these fungi (e.g.,Uromyces appendiculatus) germinate and grow, directed by the leaf (bean) surface topography toward stomata where they cease growth and develop appressoria directly over the stomatal openings. Development of the appressorium is accompanied by ameboid-like migration of the cytoplasm into the ballooning hyphal tip, DNA synthesis and nuclear division, synthesis of several “differentiation” proteins, and a rearrangement of the cytoskeleton. An orderly succession of subsequent infection structures (e.g., infection pegs, vesicles) follow in a preprogrammed sequence once the initial developmental process has been started.My research goals have been to determine what feature(s) of the host plant signals infection structure formation and how the fungus perceives these signals.

scholarly journals Heat Shock Protein 90 Is Required for Conidiation and Cell Wall Integrity in Aspergillus fumigatus

2012 ◽  
Vol 11 (11) ◽  
pp. 1324-1332 ◽  
Author(s):  
Frédéric Lamoth ◽  
Praveen R. Juvvadi ◽  
Jarrod R. Fortwendel ◽  
William J. Steinbach
Keyword(s):  
Cell Wall ◽  
Heat Shock ◽  
Heat Shock Protein ◽  
Aspergillus Fumigatus ◽  
Cellular Localization ◽  
Fluorescent Protein ◽  
Heat Shock Protein 90 ◽  
Cell Wall Integrity ◽  
Compensatory Mechanisms ◽  
Content Type

ABSTRACTHeat shock protein 90 (Hsp90) is a eukaryotic molecular chaperone. Its involvement in the resistance ofCandida albicansto azole and echinocandin antifungals is well established. However, little is known about Hsp90's function in the filamentous fungal pathogenAspergillus fumigatus. We investigated the role of Hsp90 inA. fumigatusby genetic repression and examined its cellular localization under various stress conditions. Failure to generate a deletion strain ofhsp90suggested that it is essential. Genetic repression of Hsp90 was achieved by an inducible nitrogen-dependent promoter (pniiA-Hsp90) and led to decreased spore viability, decreased hyphal growth, and severe defects in germination and conidiation concomitant with the downregulation of the conidiation-specific transcription factorsbrlA,wetA, andabaA. Hsp90 repression potentiated the effect of cell wall inhibitors affecting the β-glucan structure of the cell wall (caspofungin, Congo red) and of the calcineurin inhibitor FK506, supporting a role in regulating cell wall integrity pathways. Moreover, compromising Hsp90 abolished the paradoxical effect of caspofungin. Pharmacological inhibition of Hsp90 by geldanamycin and its derivatives (17-AAG and 17-DMAG) resulted in similar effects. C-terminal green fluorescent protein (GFP) tagging of Hsp90 revealed mainly cytosolic distribution under standard growth conditions. However, treatment with caspofungin resulted in Hsp90 accumulation at the cell wall and at sites of septum formation, further highlighting its role in cell wall stress compensatory mechanisms. Targeting Hsp90 with fungal-specific inhibitors to cripple stress response compensatory pathways represents an attractive new antifungal strategy.

scholarly journals The polyphagous plant pathogenic fungus Botrytis cinerea encompasses host-specialized and generalist populations

2019 ◽  
Author(s):  
Alex Mercier ◽  
Florence Carpentier ◽  
Clémentine Duplaix ◽  
Annie Auger ◽  
Jean-Marc Pradier ◽  
...  
Keyword(s):  
Genetic Analysis ◽  
Botrytis Cinerea ◽  
Population Genetic ◽  
Plant Pathogens ◽  
Pathogenic Fungus ◽  
Spatial Optimization ◽  
Agricultural Landscapes ◽  
Host Specialization ◽  
Population Genetic Analysis ◽  
Fungal Plant Pathogens

AbstractThe host plant is often the main variable explaining population structure in fungal plant pathogens, because specialization contributes to reduce gene flow between populations associated with different hosts. Previous population genetic analysis revealed that French populations of the grey mould pathogen Botrytis cinerea were structured by hosts tomato and grapevine, suggesting host specialization in this highly polyphagous pathogen. However, these findings raised questions about the magnitude of this specialization and the possibility of specialization to other hosts. Here we report specialization of B. cinerea populations to tomato and grapevine hosts but not to other tested plants. Population genetic analysis revealed two pathogen clusters associated with tomato and grapevine, while the other clusters co-occurred on hydrangea, strawberry and bramble. Measurements of quantitative pathogenicity were consistent with host specialization of populations found on tomato, and to a lesser extent, populations found on grapevine. Pathogen populations from hydrangea and strawberry appeared to be generalist, while populations from bramble may be weakly specialized. Our results suggest that the polyphagous B. cinerea is more accurately described as a collection of generalist and specialist individuals in populations. This work opens new perspectives for grey mold management, while suggesting spatial optimization of crop organization within agricultural landscapes.

scholarly journals The Aspergillus fumigatus sitA Phosphatase Homologue Is Important for Adhesion, Cell Wall Integrity, Biofilm Formation, and Virulence

2015 ◽  
Vol 14 (8) ◽  
pp. 728-744 ◽  
Author(s):  
Vinícius Leite Pedro Bom ◽  
Patrícia Alves de Castro ◽  
Lizziane K. Winkelströter ◽  
Marçal Marine ◽  
Juliana I. Hori ◽  
...  
Keyword(s):  
Cell Wall ◽  
Aspergillus Fumigatus ◽  
Biofilm Formation ◽  
Essential Gene ◽  
Pathogenic Fungus ◽  
Invasive Pulmonary Aspergillosis ◽  
Cell Wall Integrity ◽  
Necrosis Factor Alpha ◽  
Content Type ◽  
Opportunistic Pathogenic

ABSTRACTAspergillus fumigatusis an opportunistic pathogenic fungus able to infect immunocompromised patients, eventually causing disseminated infections that are difficult to control and lead to high mortality rates. It is important to understand how the signaling pathways that regulate these factors involved in virulence are orchestrated. Protein phosphatases are central to numerous signal transduction pathways. Here, we characterize theA. fumigatusprotein phosphatase 2A SitA, theSaccharomyces cerevisiaeSit4p homologue. ThesitAgene is not an essential gene, and we were able to construct anA. fumigatusnull mutant. The ΔsitAstrain had decreased MpkA phosphorylation levels, was more sensitive to cell wall-damaging agents, had increased β-(1,3)-glucan and chitin, was impaired in biofilm formation, and had decreased protein kinase C activity. The ΔsitAstrain is more sensitive to several metals and ions, such as MnCl2, CaCl2, and LiCl, but it is more resistant to ZnSO4. The ΔsitAstrain was avirulent in a murine model of invasive pulmonary aspergillosis and induces an augmented tumor necrosis factor alpha (TNF-α) response in mouse macrophages. These results stress the importance ofA. fumigatusSitA as a possible modulator of PkcA/MpkA activity and its involvement in the cell wall integrity pathway.

scholarly journals Deregulation of DSE1 Gene Expression Results in Aberrant Budding within the Birth Scar and Cell Wall Integrity Pathway Activation in Saccharomyces cerevisiae

2009 ◽  
Vol 8 (4) ◽  
pp. 586-594 ◽  
Author(s):  
Ivana Frýdlová ◽  
Ivana Malcová ◽  
Pavla Vašicová ◽  
Jiří Hašek
Keyword(s):  
Gene Expression ◽  
Saccharomyces Cerevisiae ◽  
Cell Wall ◽  
Daughter Cell ◽  
Fluorescent Protein ◽  
Expression Profiles ◽  
Gene Expression Profiles ◽  
Specific Protein ◽  
Cell Wall Integrity ◽  
Pathway Activation

ABSTRACT Strains of Saccharomyces cerevisiae lacking Isw2, the catalytic subunit of the Isw2 chromatin remodeling complex, show the mating type-independent activation of the cell wall integrity (CWI) signaling pathway. Since the CWI pathway activation usually reflects cell wall defects, we searched for the cell wall-related genes changed in expression. The genes DSE1, CTS1, and CHS1 were upregulated as a result of the absence of Isw2, according to previously published gene expression profiles (I. Frydlova, M. Basler, P. Vasicova, I. Malcova, and J. Hasek, Curr. Genet. 52:87-95, 2007). Western blot analyses of double deletion mutants, however, did not indicate the contribution of the chitin metabolism-related genes CTS1 and CHS1 to the CWI pathway activation. Nevertheless, the deletion of the DSE1 gene encoding a daughter cell-specific protein with unknown function suppressed CWI pathway activation in isw2Δ cells. In addition, the deletion of DSE1 also abolished the budding-within-the-birth-scar phenotype of isw2Δ cells. The plasmid-driven overexpression proved that the deregulation of Dse1 synthesis was also responsible for CWI pathway activation and manifestation of the budding-within-the-birth-scar phenotype in wild-type cells. The overproduced Dse1-green fluorescent protein localized to both sides of the septum and persisted in unbudded cells. Although the exact cellular role of this daughter cell-specific protein has to be elucidated, our data point to the involvement of Dse1 in bud site selection in haploid cells.

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